package org.hxzon.demo.lucene;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Date;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.NumericField;
import org.apache.lucene.index.FieldInfo.IndexOptions;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.index.Term;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;

public class IndexFiles {
    public static final Version luceneVersion = Version.LUCENE_34;
    public static final String FieldName_Path = "path";
    public static final String FieldName_Modified = "modified";
    public static final String FieldName_Contents = "contents";

    private IndexFiles() {
    }

    /** Index all text files under a directory. */
    public static void main(String[] args) {
        String srcPath = IndexFiles.class.getResource("/").toString().substring(5);
        String indexPath = srcPath + "/../luceneIndexed";
        String docsPath = srcPath + "/../fileToBeIndexed";
        boolean create = true;
        for (int i = 0; i < args.length; i++) {
            if ("-index".equals(args[i])) {
                indexPath = args[i + 1];
                i++;
            } else if ("-docs".equals(args[i])) {
                docsPath = args[i + 1];
                i++;
            } else if ("-update".equals(args[i])) {
                create = false;
            }
        }

        final File directoryToBeIndexed = new File(docsPath);
        if (!directoryToBeIndexed.exists() || !directoryToBeIndexed.canRead()) {
            System.out.println("Document directory '" + directoryToBeIndexed.getAbsolutePath() + "' does not exist or is not readable, please check the path");
            System.exit(1);
        }

        Date start = new Date();
        try {
            System.out.println("Indexing to directory '" + indexPath + "'...");

            Directory indexDirectory = FSDirectory.open(new File(indexPath));
            Analyzer analyzer = new StandardAnalyzer(luceneVersion);
            //Analyzer analyzer = new SmartChineseAnalyzer(luceneVersion);
            IndexWriterConfig indexWriterConfig = new IndexWriterConfig(luceneVersion, analyzer);

            if (create) {
                // Create a new index in the directory, removing any
                // previously indexed documents:
                indexWriterConfig.setOpenMode(OpenMode.CREATE);
            } else {
                // Add new documents to an existing index:
                indexWriterConfig.setOpenMode(OpenMode.CREATE_OR_APPEND);
            }

            // Optional: for better indexing performance, if you
            // are indexing many documents, increase the RAM
            // buffer.  But if you do this, increase the max heap
            // size to the JVM (eg add -Xmx512m or -Xmx1g):
            //
            // indexWriterConfig.setRAMBufferSizeMB(256.0);

            IndexWriter indexWriter = new IndexWriter(indexDirectory, indexWriterConfig);
            indexDocs(indexWriter, directoryToBeIndexed);

            // NOTE: if you want to maximize search performance,
            // you can optionally call optimize here.  This can be
            // a costly operation, so generally it's only worth
            // it when your index is relatively static (ie you're
            // done adding documents to it):
            //
            // indexWriter.optimize();

            indexWriter.close();

            Date end = new Date();
            System.out.println(end.getTime() - start.getTime() + " total milliseconds");

        } catch (IOException e) {
            System.out.println(" caught a " + e.getClass() + "\n with message: " + e.getMessage());
        }
    }

    /**
     * Indexes the given file using the given writer, or if a directory is given,
     * recurses over files and directories found under the given directory.
     * 
     * NOTE: This method indexes one document per input file.  This is slow.  For good
     * throughput, put multiple documents into your input file(s).  An example of this is
     * in the benchmark module, which can create "line doc" files, one document per line,
     * using the
     * <a href="../../../../../contrib-benchmark/org/apache/lucene/benchmark/byTask/tasks/WriteLineDocTask.html"
     * >WriteLineDocTask</a>.
     *  
     * @param writer Writer to the index where the given file/dir info will be stored
     * @param file The file to index, or the directory to recurse into to find files to index
     * @throws IOException
     */
    static void indexDocs(IndexWriter writer, File file) throws IOException {
        // do not try to index files that cannot be read
        if (file.canRead()) {
            if (file.isDirectory()) {
                String[] files = file.list();
                // an IO error could occur
                if (files != null) {
                    for (int i = 0; i < files.length; i++) {
                        indexDocs(writer, new File(file, files[i]));
                    }
                }
            } else {

                FileInputStream fis;
                try {
                    fis = new FileInputStream(file);
                } catch (FileNotFoundException fnfe) {
                    // at least on windows, some temporary files raise this exception with an "access denied" message
                    // checking if the file can be read doesn't help
                    return;
                }

                try {

                    // make a new, empty document
                    Document doc = new Document();

                    // Add the path of the file as a field named "path".  Use a
                    // field that is indexed (i.e. searchable), but don't tokenize 
                    // the field into separate words and don't index term frequency
                    // or positional information:
                    Field pathField = new Field(FieldName_Path, file.getPath(), Field.Store.YES, Field.Index.NOT_ANALYZED_NO_NORMS);
                    pathField.setIndexOptions(IndexOptions.DOCS_ONLY);
                    doc.add(pathField);

                    // Add the last modified date of the file a field named "modified".
                    // Use a NumericField that is indexed (i.e. efficiently filterable with
                    // NumericRangeFilter).  This indexes to milli-second resolution, which
                    // is often too fine.  You could instead create a number based on
                    // year/month/day/hour/minutes/seconds, down the resolution you require.
                    // For example the long value 2011021714 would mean
                    // February 17, 2011, 2-3 PM.
                    NumericField modifiedField = new NumericField(FieldName_Modified);
                    modifiedField.setLongValue(file.lastModified());
                    doc.add(modifiedField);

                    // Add the contents of the file to a field named "contents".  Specify a Reader,
                    // so that the text of the file is tokenized and indexed, but not stored.
                    // Note that FileReader expects the file to be in UTF-8 encoding.
                    // If that's not the case searching for special characters will fail.
                    doc.add(new Field(FieldName_Contents, new BufferedReader(new InputStreamReader(fis, "UTF-8"))));

                    if (writer.getConfig().getOpenMode() == OpenMode.CREATE) {
                        // New index, so we just add the document (no old document can be there):
                        System.out.println("adding " + file);
                        writer.addDocument(doc);
                    } else {
                        // Existing index (an old copy of this document may have been indexed) so 
                        // we use updateDocument instead to replace the old one matching the exact 
                        // path, if present:
                        System.out.println("updating " + file);
                        writer.updateDocument(new Term(FieldName_Path, file.getPath()), doc);
                    }

                } finally {
                    fis.close();
                }
            }
        }
    }
}
